1. Field of the Invention
The present invention relates to observer-compensators of the type employed in motor systems. More particularly, the present invention relates to a novel dynamic observer-compensator for use in electric as well as other types of motor systems for substantially eliminating unmeasurable disturbance forces. 2. Description of the Prior Art
Motors are employed in numerous types of positioning devices comprising aircraft, missiles, machine tools, etc. in the form of rotary or linear actuators used to rapidly and accurately position a moving part of the motor. All types of motor actuators have unmeasurable resistance forces. When an electric motor is continuously moving, there are created unmeasurable disturbance forces as well as cogging forces. The major unmeasurable disturbance forces result from outside forces and variable friction forces in the system as well as cogging forces in the electric motors. Cogging forces result from parasitic, magnetic forces of motor magnets on the iron core and are not constant. The cogging force varies with position, direction, speed, size, etc. as well as magnetic characteristics of the materials used in the motors. Heretofore, it has not been possible to map or anticipate or measure these unmeasurable and variable forces. Had the prior art been able to measure these unmeasurable disturbance forces, it would have been possible to eliminate them.
Standard feedback and feed forward control systems for electric motors are known and are commonly used when designers attempt to rapidly position a motor along a series of positions defining a desired trajectory. It is desirable to control the trajectory of a motor without lagging errors and to rapidly position a working tool at an end position without any overshoot of oscillations whatsoever.
Automatic wire bonders that are used by the semiconductor industry are known to employ desired position trajectories in order to bond fine wire connections between a pad on the semiconductor chip and a lead frame or carrier. The automatic wire bonder shown and described in U.S. Pat. No. 4,266,710 can be controlled by command signals to follow precise predetermined paths which result in precise and repeatable loops of fine wire interconnections provided that the X, Y and Z drive motors of the system are not pushed to their extreme limits where the aforementioned unmeasurable forces become so significant that a compromise in effecting the speed of obtaining a desired position has become necessary.
Heretofore, attempts have been made to compensate for unwanted unmeasurable forces in high speed, high performance precise positioning rotary and linear motors. The prior art does not teach or suggest any system for measuring, modeling or replicating these unmeasurable forces including cogging forces in any electric motor system. Accordingly, it would be highly desirable to provide a dynamic real time system for replicating unmeasurable disturbance forces which would allow an increase in the speed of operation and performance of electric motor systems as well as other types of motor systems.